2009 Yamaha YZ125Y Service Manual

Wiring diagrams, specifications, and repair sequences for the YZ125Y, covering operation, inspection, and maintenance. PN LIT-11626-22-54.

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Document Details

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Document Number / Seller:
27780 / Richard Campbell
File Size:
9.07 MB
File Type:
PDF
Language:
Pages:
231
Printable:
Yes
Category:
Bike
Last updated / verified
Apr 2, 2025

Models Covered & Key Technical Specifications

Yamaha YZ125Y (2009) Service Manual Comprehensive Diagnostics & Repair Procedures | Wiring & Specs

  • Documented Spark Plug Torque: 20 Nm
  • Calibrated Cylinder Head Torque: 28 Nm
  • Authorized Clutch Boss Torque: 80 Nm
  • Core Front Wheel Axle Torque: 105 Nm
  • Rated Rear Wheel Axle Torque: 125 Nm
  • Principal Steering Ring Nut Torque: 7 Nm

Manual Description & Preview

Systematic Performance Shop Manual: Yamaha YZ125Y Service Manual - Comprehensive Diagnostics & Repair Procedures (2009) Maintenance-Registry

Design-Core: YZ125Y // Model-Designation: 2009 Yamaha YZ125Y // Design-Core: Owner's Service Manual Logic.

Table of Contents Summary

  • General Information
  • Specifications
  • Engine
  • Chassis
  • Electrical

    Systems and Procedures

    Parts identification is covered for the entire machine, including important labels and their locations. Removal procedures are documented for various components, including the front and rear brakes, and the steering system. Technical specifications are provided for engine type, displacement, bore x stroke, and compression ratio. Factory specifications are documented for clutch type, transmission gear ratios, and tire specifications. Engine rebuild procedures are documented for the cylinder head, cylinder, and piston.

    Key Specifications

    Engine Type: Liquid cooled 2-stroke, gasoline Displacement: 124 cm3 (4.36 Imp oz, 4.19 US oz) Bore x Stroke: 54 × 54.5 mm (2.126 × 2.146 in) Transmission Type: Constant mesh, 6-speed Front Wheel Travel: 300 mm (11.8 in) Rear Wheel Travel: 315 mm (12.4 in)

    Torque Specifications

Identifier Technical-Path Framework
Spark Plug M14S x 1.25 20 Nm
Cylinder Head Nut M8 x 1.25 28 Nm
Clutch Boss M16 x 1.0 80 Nm
Front Wheel Axle Nut M16 x 1.5 105 Nm
Rear Wheel Axle Nut M20 x 1.5 125 Nm
Steering Ring Nut (Final) M28 x 1.0 7 Nm

FAQ

Specify the **applicable** lubrication requirements for the YZ125Y? keyboard_arrow_down

Yamaha recommends specific oils like Yamalube "2-R" for the premix at a 30:1 ratio, and Yamalube 4 (10W-40) or SAE 10W-40 SE motor oil for the transmission, ensuring proper component longevity.

What is the **exact** testing parameters for the clutch springs on this model? keyboard_arrow_down

40.1 mm (1.579 in) is the standard free length for the clutch springs; values outside the of 38.1 mm (1.500 in) indicate they need replacement.

Calculate the **specific** diagnostic procedures for brake fluid replacement? keyboard_arrow_down

Brake fluid replacement involves draining the system, ensuring no air is trapped, and then refilling with DOT #4 fluid, with careful attention to avoiding contamination, as detailed on page 3-17.

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